Tube bottom and heat exchanger

ABSTRACT

A tube bottom for a heat exchanger, with a bottom region having slot-type openings, wherein the slot-type openings are rimmed by eyelets and the tube bottom has an attached rim region. Formed between the eyelets and the attached rim region is a U-shaped trough as a receiving region for the foot of a box-like cover. The U-shaped trough has an inner first wall, the attached rim region and a second wall forming the trough bottom, wherein the inner first wall has at least one hump-like raised portion in the continuation of an eyelet on a side oriented toward the U-shaped trough, which bounds the breadth of the U-shaped trough between the attached rim region and the first wall and extends from the trough bottom to that end region of the eyelet oriented toward the U-shaped trough. A depression is formed in the hump-like raised portion.

This nonprovisional application is a continuation of InternationalApplication No. PCT/EP2015/065989, which was filed on Jul. 13, 2015, andwhich claims priority to German Patent Application No. 10 2014 213758.6, which was filed in Germany on Jul. 15, 2014, and which are bothherein incorporated by reference.

BACKGROUND OF THE INVENTION

Field of the Invention

The invention relates to a tube bottom for a heat exchanger, having abottom region which has slot-type openings, wherein the slot-typeopenings are rimmed by eyelets and the tube bottom has an attached rimregion, a U-shaped trough being arranged between the eyelets and theattached rim region, the U-shaped trough being formed by an inner firstwall, the attached rim region and a second wall forming the troughbottom. The invention also relates to a heat exchanger.

Description of the Background Art

Coolant coolers can have a plurality of tubes, which can be traversed bya medium and at the same time can be surrounded by a medium. In a knownconstruction, the tubes are received at their ends in tube bottoms. Thetube bottoms have a number of openings corresponding to the number oftubes, one tube each being inserted into an opening. The tube is closedby a box-like cover to form a collecting box. For this purpose, thebox-like cover is inserted into the tube bottom and is connected to it.

A multi-chamber tube is known from DE 199 20 102 B4, which correspondsto U.S. Pat. No. 6,343,645, which is incorporated herein by reference.This multi-chamber tube can be inserted into correspondingly adaptedtube bottoms so as to form a heat transfer block. Ribbed elements can bearranged between the multi-chamber tubes, which improve the heattransfer.

DE 10 2011 085 479 A1, which corresponds to US 2014/0262187, which isincorporated herein by reference, discloses a heat exchanger which hastwo tube bottoms, in each of which a plurality of tubes is received attheir ends. Furthermore, a box-like cover is inserted into the tubebottoms, whereby a heat transfer block which can be flowed through isformed.

A heat exchanger is known from DE 103 43 239 A1, which corresponds to US2007/0000657, which is herein incorporated by reference, and which has aheat transfer block having a plurality of tubes received at the ends intube bottoms. A flow-through heat transfer block is formed by box-likecovers, which are inserted into the tube bottoms and are connected tothe tube bottoms.

A bottom plate of a collecting box for a heat exchanger is known from DE10 2008 011 579 A1. The bottom plate forms the so-called tube bottom,which has a plurality of openings into which tubes can be inserted. Abox-like cover can also be inserted into the tube bottom shown, wherebya flow-through heat transfer block can be produced.

A disadvantage of the devices in the art is, in particular, that thetube bottoms can be adapted only with difficulty to openings ofdifferent widths when the width of the tube bottom remains otherwiseunchanged. Therefore, an increased adjustment effort is required inorder to provide tube bottoms of the same width with openings ofdifferent widths. In particular, the receiving area of the tube bottoms,into which the box-like cover is inserted, must be specially adapted toachieve a sufficiently high tightness. For this reason, tube bottoms ofdifferent widths are used for openings of different widths, resulting invarying dimensions of the heat exchangers that are formed. Thisnecessitates a higher assembly effort, which adversely affects theassembly time and costs.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a tubebottom which while maintaining the same width of the tube bottom can beadapted to openings of different widths in the tube bottom. Furthermore,the object of the present invention is to provide a heat exchanger withsuch a tube bottom.

An exemplary embodiment of the invention relates to a tube bottom for aheat exchanger, having a bottom region which has slot-type openings,wherein the slot-type openings are rimmed by eyelets and the tube bottomhas an attached rim region, a U-shaped trough being arranged for thebottom of a box-like cover between the eyelets and the attached rimregion, wherein the U-shaped trough is formed by an inner first wall,the attached rim region and a second wall forming the trough bottom,wherein the inner first wall has at least a hump-like portion in theform of an extension on the side oriented towards the U-shaped trough,which bounds the breadth of the U-shaped trough between the attached rimregion and the first wall and which extends from the bottom of thetrough to the end region of the eyelet facing the U-shaped trough, whichserves to produce a lead-in chamfer for tubes.

In this case, it is advantageous if a material displacement towards theside of the first wall facing away from the U-shaped trough is formedthrough the molded-in depression,

By means of a hump-like portion from the inner wall, the breadth of theU-shaped trough can be particularly advantageously bounded. At the sametime, the height of the U-shaped trough on the inside can be defined bythe hump-like portion. The hump-like portion can in this case beadapted, in particular, as a function of the respective width of theeyelets. In this way, tube bottoms with an identical basic width can beproduced which each have differently wide openings and eyelets. This isadvantageous because the same production machines can be used for thedifferent tube bottoms and only the respective thermoforming tools needto be adapted. In addition, a standardized width for the tube bottomscan thus be ensured even in tubes of different widths, whereby the spacerequirements of the heat exchangers produced can be standardized.

By means of a formed depression, a targeted material displacement can beachieved. A greater material thickness can be achieved, in particular,on the side of the inner wall oriented away from the U-shaped troughsince, in addition, material is displaced there by the molding-in of thedepression. This is particularly advantageous to be able to producesufficiently large-dimensioned lead-in chamfers for mounting the tubeson the tube bottom.

The transition region between the U-shaped trough and the end region ofthe eyelet can be individually configured by adapting the hump-likeportion, so that sufficient guidance and fixing is provided for thebottom region of a box-like cover, and at the same time, sufficientmaterial thickness for the formation of lead-in chamfers to facilitatetube installation remains.

The deflection of the hump-like portion can increase from the inner walloutwards from the bottom of the trough towards the respective eyelet.This is advantageous since an oblique surface is produced which facesthe U-shaped trough and can serve as a centering aid for the bottomregion of a box-like cover.

The hump-like portion can extend into the bottom region and at leastpartly surrounds the eyelet. This is particularly advantageous to createhigher stability and, at the same time, to achieve softer transitionsbetween the eyelet and the hump-like portion or the inner wall.

It is also expedient if the first wall has a lead-in chamfer on its sidefacing away from the U-shaped trough, the lead-in chamfer being arrangedon the hump-like portion, and the lead-in chamfer producing a taperingof the slot-type openings rimmed by the eyelets.

A lead-in chamfer is advantageous for facilitating the insertion of thetubes into the openings rimmed by the eyelets. In this case, it isparticularly advantageous if the lead-in chamfers are formed in regionsof the tube bottom, which have a sufficient material thickness to form asufficiently long lead-in chamfer.

In addition, it is advantageous if the lead-in chamfer is formed on themolded-in depression. A lead-in chamfer on the molded-in depression isadvantageous since a material accumulation is produced by thedepression, which allows for a lead-in chamfer with sufficiently largedimensions.

An exemplary embodiment provides that the slot-type openings have twoopposing narrow sides and two opposing wide sides, wherein a slot-typeopening is tapered by lead-in chamfers on the narrow side and on the endregions of the wide sides facing the narrow side. It is particularlyadvantageous if lead-in chamfers are formed on both the narrow side andon the wide sides to enable a production that is as exact and simple aspossible. In particular, the introduction of the tubes is facilitated inthis way.

Furthermore, the hump-like portion and/or the depression is impressed inthe hump-like portion into the tube bottom and/or can be formed bythermoforming. The impressing and/or thermoforming is advantageous toproduce the hump-like portion and the depression with the sameproduction methods as are used for the rest of the tube bottom. Thissimplifies production and thus reduces costs.

The first wall and the surface of the hump-like portion that areoriented towards the U-shaped trough can be oriented towards the troughbottom at an angle greater than 90 degrees. An angle greater than 90degrees is advantageous to produce a slope which allows for anadvantageous insertion of the bottom region of a box-like cover into theU-shaped trough.

The side of the hump-like portion facing the U-shaped trough can form acentering aid for the insertion of the box-like cover into the U-shapedtrough.

An embodiment of the invention relates to a heat exchanger with two tubebottoms, wherein the heat exchanger has a plurality of tubes which arearranged parallel to each other and are accommodated at their end ineach case in an opening of a tube bottom rimmed by an eyelet, whereinthe tubes are inserted along the lead-in chamfers into the respectiveopenings, wherein a box-like lid, which is connected to the respectivetube bottom, is inserted into the U-shaped trough of each tube bottom.

Such a heat exchanger is particularly advantageous since it isparticularly easy to install. The lead-in chamfers allow for easypositioning of the tubes in the openings. Furthermore, the centering aidon the hump-like portion allows for simple positioning of the box-likecover in the U-shaped trough.

Further scope of applicability of the present invention will becomeapparent from the detailed description given hereinafter. However, itshould be understood that the detailed description and specificexamples, while indicating preferred embodiments of the invention, aregiven by way of illustration only, since various changes, combinations,and modifications within the spirit and scope of the invention willbecome apparent to those skilled in the art from this detaileddescription.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description given hereinbelow and the accompanying drawingswhich are given by way of illustration only, and thus, are not limitiveof the present invention, and wherein:

FIG. 1 is a sectional view of a tube bottom,

FIG. 2 is a sectional view of a tube bottom, wherein the transitionbetween the eyelet and the U-shaped trough is formed by a hump-likeportion,

FIG. 3 is a view of two contours each of a U-shaped trough,

FIG. 4 is a perspective view of a tube bottom, wherein the opening orthe eyelet is formed very broad,

FIG. 5 is a perspective view of an alternatively designed tube bottom,the openings or the eyelets being designed less broadly than in thepreceding FIG. 4, wherein the hump-like portion has a plateau,

FIG. 6 is a perspective view of an alternative tube bottom, wherein theplateau is designed flatter than the tube bottom shown in FIG. 5,

FIG. 7 is a sectional view through a tube bottom according to theinvention, wherein a depression is formed in the hump-like portion fromabove, which depression forms a material accumulation on the downwardlydirected side of the hump-like portion,

FIG. 8 is a perspective view of the tube bottom according to FIG. 7,

FIG. 9 is a view of the underside of the tube bottom according to FIGS.7 and 8,

FIG. 10 is a sectional view through two tube bottoms, wherein one tubebottom with a less broad eyelet is shown, and one tube bottom with abroader eyelet, and

FIG. 11 is a perspective view of a tube bottom with two differentembodiments of a lead-in chamfer.

DETAILED DESCRIPTION

FIG. 1 shows a cross-section through a conventional tube bottom 1. Thetube bottom 1 has a plurality of openings 3 which are arranged on theflat bottom region 2. The openings 3 are each rimmed by eyelets 4. Rightand left of the openings 3 are U-shaped troughs 5, which are essentiallyformed between an attached rim region 6 and an inner wall 7 extendingparallel thereto.

The U-shaped troughs 5 are in each case terminated in the downwarddirection by the trough bottom 8. Tubes can be inserted into theopenings 3 along the direction 9.

FIG. 2 shows a sectional view through an alternatively designed tubebottom 10, which in particular has a different geometry for the U-shapedtrough 14. Specifically, the transition of the eyelets 13 toward theU-shaped trough 14 is designed differently.

The tube bottom 10 has a bottom region 11 in which a plurality ofopenings 12 are formed, which are bordered by collar-like eyelets 13.The end regions of the eyelets 13 located on the left and right areterminated by hump-like projections 22, which can be introduced into theinner wall 17 of the tube bottom 10, for example, by an impressingprocess. The eyelets 13 project into the U-shaped trough 14 through thehump-like portions 22. The U-shaped trough 14 is formed by the attachedrim region 15, the inner wall 17 and the trough bottom 24. The upperregion 16 of the attached rim region 15 is further angled as compared tothe lower region 15.

In particular, the inner wall 17 is at an angle greater than 90° to thetrough bottom 24. The hump-like portion 22, on its side facing outwardstowards the attached rim region 15, forms a surface 21, which inparticular can be used as a centering aid for inserting a box-like coveror the bottom region of the box-like cover. The surface 21 is inclinedsuch that a box-like cover inserted from above is automaticallydeflected into the U-shaped trough 14 provided for this purpose.

The reference numbers 18 and 19 show different possible positions for abottom region of a box-like cover. The limitation 20 shows the maximumpossible inner position for a bottom region. A further displacement ofthe bottom region inwards would lead to faulty or incorrect mounting.Each arrangement of a bottom region, which is located to the left of themarking 20, with the aid of the centering aid 21 leads to an exact fitof the bottom region in the U-shaped trough 14. The tube bottom 10 ofFIG. 2 is likewise already known from the prior art.

FIG. 3 shows two cross-sections of U-shaped troughs in each case of atube bottom. A contour of a U-shaped trough with a hump-like shape isshown represented by the reference number 30, for example, in FIG. 2. Acontour of a U-shaped trough is represented by reference number 31, asshown by way of example in FIG. 1. FIG. 3 illustrates the differentconstruction, in particular the different width or the different heighton the inner side of the different U-shaped troughs.

FIG. 4 shows a perspective view of a tube bottom 10 as has already beenshown in FIG. 2. In FIG. 4 it can be seen in particular that thehump-like portion 22 has a flat surface 21, which is directed to theattached rim region 15, which also serves as a centering aid. Thehump-like portion 22 is formed from the otherwise flat inner wall 17,for example, by thermoforming or impressing.

The hump-like portion 22 extends not only over the inner wall 17, butalso into the bottom region 11, where in particular the partial region23 of the hump-like portion 22 also rims the eyelet 13 along its widesides.

FIG. 5 shows an alternative embodiment of a tube bottom 40. The tubebottom 40 has a bottom region 41, which has a plurality of openings 42,which are bordered by collar-like eyelets 43.

In the exemplary embodiment shown in FIG. 5, the eyelets 43 or theopenings 42, respectively, have a shorter extent in the breadth of thetube bottom 40. The breadth of the tube bottom 40 is measured here aswell as in the other exemplary embodiments in each case from an attachedrim region 45 to the rim region situated opposite the latter.

To compensate for this shortening of the openings 42 or of the eyelets43 in comparison with the embodiment of FIG. 4, the hump-like portion 48has an extended region which is designed as a plateau 50. As in thepreceding FIG. 4, a partial region 49 of the hump-like portion 48 alsopartially encloses the wide sides of the respective eyelet 43. Thehump-like portion 48 also has a surface facing the attached rim region45, which surface can be used as a centering aid.

The U-shaped trough 44 is formed by the attached rim region 45, theinner wall 47 and the trough bottom 51. The attached rim region 45 hasslots which can serve for fastening the box-like cover in the tubebottom 40. The fastening of the box-like cover can be achieved, forexample, by clamping, by providing corrugated slot crimping or with theaid of other known fixing elements.

The hump-like portion 48, in particular the plateau 50 and the partialregion 49, are likewise formed by an impressing process or by athermoforming process from the inner wall 47 or the bottom region 41.

The plateau 50 serves to bridge between the U-shaped trough 44 and theeyelet 43. It must preferably be sufficiently flat so that enoughmaterial remains on the underside of the tube bottom 40 to be able toform a sufficient lead-in chamfer and at the same time be high enough toprovide sufficient height of the U-shaped trough 44 on the inside. Theplateau 50 in the exemplary embodiment of FIG. 5 is designed high. Thisallows for sufficient height of the U-shaped trough 44 but is notoptimal with respect to the lead-in chamfer on the underside. Thefollowing FIG. 6 shows a plateau 70 which is flatter and is thus moreadvantageous with respect to the formation of a lead-in chamfer, but atthe same time requires lower height of the U-shaped trough, which isdisadvantageous.

FIG. 6 shows a further alternative exemplary embodiment of a tube bottom60, which has a bottom region 61 with an opening 62 arranged therein anda collar-like eyelet 63. The opening 62 or the eyelet 63 in FIG. 6 has arelatively short extent in the width of the tube bottom 60. For thisreason, the hump-like portion 68 likewise has a plateau 70, wherein theplateau 70 is shorter and flatter than the plateau 50 of the precedingFIG. 5. For this purpose, the partial region 69, which comprises thewide sides of the eyelets 63, is formed even further from the plane ofthe bottom region 61 than the plateau 70. The partial region 69 forms aU-shaped bead which surrounds the eyelet 63 both on the wide sides andon the narrow side.

The tube bottom 60 also has a U-shaped trough 64. Like in the precedingfigures, the U-shaped trough 64 is formed by an attached rim region 65,an inner wall 67 situated opposite the latter and a trough bottom 71.The attached rim region 65 likewise has an outwardly angled partialregion 66 in the upper region. The hump-like portion 68 also has asurface directed toward the attached rim region 65, which surface can beused as a centering aid.

FIG. 7 shows an embodiment of a tube bottom 80 according to theinvention. The tube bottom 80 has a bottom region 81. Openings 82, whichare rimmed by collar-like eyelets 83, are formed in the bottom region81. The openings 82 have two opposing narrow sides 98 and two opposingwide sides 97. Correspondingly, the eyelets 83, which surround theopenings 82, each have two narrow sides 98 and two wide sides 97. TheU-shaped trough 84 is formed by an attached rim region 85 and an innerwall 87 opposing the latter and the trough bottom 94.

A hump-like portion 88 is formed from the inner wall 87 and the bottomregion 81, which, in particular with the surface 91 facing the attachedrim region 85, forms a smaller angle with respect to the attached rimregion 85 than the inner wall 87. In addition, the hump-like portion 88has a depression 90 molded in from above, which is arranged immediatelyadjacent to the end region of the eyelet 83.

Through the depression 90, which can also be molded into the hump-likeportion 88 by an impressing process or by thermoforming, a materialdisplacement downwards takes place which allows for a formation of alead-in chamfer in particular on the downwardly directed side 96 of theinner wall 87 or of the bottom region 81. Due to the materialdisplacement, the lead-in chamfer can be made larger overall, wherein inparticular, the extent of the lead-in chamfer along the insertiondirection of the tube can be enlarged. This simplifies the insertion ofthe tubes and thus allows for a more stable installation process. Thelead-in chamfer is not shown in FIG. 7.

In FIG. 7, a partial region 89 of the hump-like portion 88 also rims thewide sides 97 of the eyelet 83. Furthermore, the hump-like portionprovides a sufficient height of the U-shaped trough 84, whereby a securepositioning of a box-like cover can be ensured.

FIG. 8 shows a further perspective view of the tube bottom 80, as hasalready been shown in FIG. 7. In particular, it can be seen in FIG. 8that the depression 90 is formed by a rectilinear depression runningparallel to the U-shaped trough 84. Furthermore, FIG. 8 shows that boththe end region 99 of the wide sides 97 and the narrow side 98 of theeyelet 83 or the opening 82 are enclosed by the partial region 89 of thehump-like portion 88. Moreover, the hump-like portion 88 also forms aflat, inclined surface 91, which can be used as a centering aid for thebottom region of a box-like cover.

FIG. 9 shows a view of the tube bottom 80 of FIGS. 7 and 8, with aviewing direction from below onto the opening 82 or the eyelet 83. Theside 96 of the inner wall 87 facing away from the U-shaped trough 84 canbe seen. In addition, FIG. 9 particularly shows the lead-in chamfers 92and 93, which run both on the narrow side 98 of the eyelet 83 as well ason the end regions 99 of the two wide sides 97. These lead-in chamfers92 and 93 are formed, in particular, in the region of the materialdisplacement produced by the depression 90. In particular, these servefor the simplified positioning and assembly of the tubes in the openings82.

The embodiment according to the invention, as shown in FIGS. 7 to 9, canin particular also be combined with the preceding embodiments for lesswide eyelets 43 and for wider eyelets 13 of FIGS. 4 to 6. In particular,the additional depression 90, which leads to a material displacement, isadvantageous in this case to obtain the required material on theunderside of the eyelets 83 to be able to form sufficiently dimensionedlead-in chamfers 92 and 93. This is due in particular to the fact thatthe tube bottoms, as shown in FIGS. 1 to 9, are preferably produced froma plate-like material by using several thermoforming processes. In eachthermoforming process, material compression and material stretching takeplace, which ultimately lead to a thinning of the base material. Byintroducing additional depression, this partially disadvantageousthinning can be counteracted and, specifically, material can bedisplaced to defined regions.

FIG. 10 shows a comparative view of an embodiment with a tube bottom 80with a less wide eyelet 83 and a wider eyelet 13 as already shown inFIG. 4. In particular, it can be seen in FIG. 10 that the U-shapedtrough 14 or 84 is designed identical, irrespective of the width of theeyelet 13 or 83. In the case of the less-wide eyelet 83, the depression90 is molded into the hump-like portion 88, as shown in FIGS. 7 to 9. Inthe case of the wider eyelet 13, this depression is not provided, asalready shown in FIG. 4. In an alternative embodiment, however, thedepression can also be combined with a wide eyelet 13.

FIG. 11 shows a comparative view of two lead-in chamfers 101 or 102, ascan be formed as a function of the width of the eyelet, which isdesignated by the reference number 100. The lead-in chamfers 101 and 102in particular form the front-side lead-in chamfers, which are formed onthe respective narrow side of the eyelet 100. Preferably, the lead-inchamfer formed on the narrow side has an angle of approximately 40° withrespect to a vertical, while the lead-in chamfers at the end regions ofthe wide sides preferably have an angle of approximately 30° to thevertical. These values are exemplary and do not particularly limit thedesign of the individual embodiments.

The embodiments of the preceding FIGS. 1 to 11 are exemplary andpartially represent embodiments as are known from the prior art. Inparticular, a combination of the features of the embodiments known fromthe prior art, which are shown in FIGS. 1 to 6, and the features of theembodiments according to the invention, which are shown in FIGS. 7 to 9,is possible at any time. The individual embodiments of the figures haveno limiting character, in particular with respect to the selection ofthe material, the arrangement of the individual elements and thedimensioning of the respective elements.

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are to beincluded within the scope of the following claims.

What is claimed is:
 1. A tube bottom for a heat exchanger, the tubebottom comprising: a bottom region with slot-type openings rimmed byeyelets, the tube bottom having an attached rim region; and a U-shapedtrough formed between the eyelets and the attached rim region as areceiving area for the bottom of a box-like cover, the U-shaped troughbeing formed by an inner first wall, the attached rim region and asecond wall forming a trough bottom, wherein the inner first wall has atleast one hump-like portion in an extension of an eyelet on a sidefacing the U-shaped trough, which bounds a breadth of the U-shapedtrough between the attached rim region and the first wall and extendsfrom the trough bottom to the end region of the eyelet facing theU-shaped trough, and wherein a depression is formed in the hump-likeportion as a lead-in chamfer for tubes.
 2. A tube bottom according toclaim 1, wherein a displacement of the material towards the side of thefirst wall facing away from the U-shaped trough is formed by themolded-in depression.
 3. A tube bottom according to claim 1, wherein adeflection of the hump-like portion from the inner wall increases fromthe trough bottom towards the respective eyelet.
 4. A tube bottomaccording to claim 1, wherein the hump-like portion extends into thebottom region and at least partly surrounds the eyelet.
 5. A tube bottomaccording to claim 1, wherein the first wall has a lead-in chamfer onits side facing away from the U-shaped trough, wherein the lead-inchamfer is arranged on the hump-like portion and the lead-in chamfercreates a tapering of the slot-type openings rimmed by the eyelets.
 6. Atube bottom according to claim 5, wherein the lead-in chamfer is formedon the molded-in depression.
 7. A tube bottom according to claim 5,wherein the slot-type openings have two opposing narrow sides and twoopposing wide sides, wherein a slot-type opening is tapered by lead-inchamfers on the narrow side and on the end regions of the wide sidesfacing the narrow side.
 8. A tube bottom according to claim 1, whereinthe hump-like portion and/or the depression is impressed into the tubebottom in the hump-like portion or molded in by thermoforming.
 9. A tubebottom according to claim 1, wherein the first wall and the surface ofthe hump-like portion oriented to the U-shaped trough are directedtowards the trough bottom at an angle of more than 90 degrees.
 10. Atube bottom according to claim 1, wherein the surface of the hump-likeportion facing the U-shaped trough provides a centering aid forinserting the box-like cover into the U-shaped trough.
 11. A heatexchanger with two tube bottoms according to claim 1, wherein the heatexchanger has a plurality of tubes, which are arranged parallel to eachother and are accommodated at their ends in each case in an opening of atube bottom rimmed by an eyelet, wherein the tubes are each inserted inrespective openings along the lead-in chamfers, and wherein a box-likecover, which is connected to the respective tube bottom, is insertedinto the U-shaped trough of each tube bottom.